The present invention relates to a parking aid for vehicles, and more particularly to a parking aid for vehicles approaching an obstacle such as the wall of a garage or the like.
More particularly, the invention relates to a signal-generating parking aid of the type in question.
When a vehicle approaches a stationary obstacle, for example the wall of a garage or the like, there is often the problem of determining just when to stop the vehicle so that it will not contact the obstacle. This problem is particularly acute if the vehicle is backing up, but often also exists if the vehicle moves forwardly because the shape of the hood, a protruding front bumper or some similar problem may make it impossible for the operator to determine from the front seat whether the vehicle is about to contact the obstacle. It has been proposed, for example in German Gebrauchsmuster No. 77 36 527, to mount in front of a garage wall a horizontal plank by means of telescopable supports and to arrange a switch in the path of the plank which recedes on its telescopable supports when pushed by the approaching vehicle. When the switch is closed by engagement with the plank an optical signal is generated to warn the driver that the vechicle must be stopped to avoid contact with the garage wall. However, the plank can recede from the vehicle only to a limited extent and the driver cannot instantaneously stop the vehicle when the signal light comes on. The result is that due to the time lost between energization of the signal light and activation of the vehicle brake by the driver, and the inertia of the vehicle which must be overcome before it comes to a full stop, the plank is fully pressed throughout its entire path of resiliency and is pushed up against its abutment so that there is still a rather strong impact before the vehicle comes to a stop. A rubber strip mounted on the plank can mitigate this problem to some extent, but cannot entirely avoid it. Moreover, one of the contacts of the switch is a stiff length of wire which hangs down behind the plank and is engaged by the plank as the same recedes from a contacting vehicle; this length of wire is deformed each time the arrangement operates and there is therefore no guarantee of reliable operation from instance to instance. Also, if the driver should happen to be inattentive or distracted there is the danger that the plank, the contact, the vehicle and under some circumstances even the wall behind the plank, may become damaged by too hard an impact. Finally, the plank must always be mounted and adjusted in such a way that it is exactly located at the level of the vehicle bumper, which is not only somewhat tedious but also prevents reliable operation of the arrangement in circumstances in which different vehicles use the same parking location.
Another approach, suggested in German Gebrauchsmuster No. 77 37 528, proposes the use of a rod the lower end of which is connected relatively close to the floor and which extends upwardly parallel to the wall, carrying at its upper end a disk. This arrangment relies upon the fact that when the rod is contacted by an approaching vehicle it will start to vibrate or oscillate so that the moving disk constitutes a signal for the vehicle operator. However, here as in the preceding construction the time between the moment at which the disk begins to oscillate and the time at which the vehicle contacts the wall, is too small to effectively and under all circumstances prevent the possibility of damage to the vehicle, the indicator rod and/or the wall.